Sodium 2-[methyl(1-oxododecyl)amino]ethanesulphonate

Endpoint summary

Description of key information

The daily oral (dietary) administration of the read-across source substance sodium methyl cocoyl taurate (SMCT) to rats (Sprague Dawley strain, bred at Harlan UK Ltd.) did not produce any toxicological changes considered to be related to treatment. The no-effect level was greater than 1.0% of SMCT in the diet, equivalent to 500 mg/kg bw/d.

This study for the source substance SMCT is used as read-across to the registered (target) substance SMLT. See section 13 for the full read-across justification.

Key value for chemical safety assessment

Toxic effect type:

dose-dependent

Repeated dose toxicity: via oral route - systemic effects

Link to relevant study records

Reference

Endpoint:

sub-chronic toxicity: oral

Type of information:

experimental study

Adequacy of study:

key study

Study period:

1995

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

This study for the source substance SMCT is used as read-across to the registered (target) substance SMLT. See section 13 for the full read-across justification.

Reason / purpose for cross-reference:

read-across: supporting information

Qualifier:

according to guideline

Guideline:

OECD Guideline 407 (Repeated Dose 28-Day Oral Toxicity Study in Rodents)

Deviations:

no

GLP compliance:

yes

Limit test:

no

Species:

rat

Strain:

Sprague-Dawley

Sex:

male/female

Details on test animals or test system and environmental conditions:

Test System
The rat (Sprague Dawley strain obtained from Harlan UK Ltd.) was selected as the test species because of the well recognised methods which are available for toxicological bioassay in this species and its use in earlier short-term studies.

A total of 100 rats (50 male and 50 female were obtained from Harlan UK Ltd. on 23 Jun 1994. At the start of the study the rats were 5-6 weeks old and had a body weight range of 186.8 - 209.5g (males) and 144.2 - 173.4g (females).

Pre-test health check
Five days before the start of the study a blood sample of approximately 0.2ml was removed from each animal via a lateral tail vein and subjected to a full haematological examination.

Animal numbering and ID
Five days before the start of the study, each animal was weighed and 80 rats were selected and allocated randomly to one of the four groups using a stratified randomisation procedure based on body weight. The animals were implanted with an electronic tag (RS Biotech, Finedon, Northants.) for individual identification.

Animal Husbandry
The study was carried out in room 7 of the SPF Unit. The animals were multiple housed in polycarbonate (Markrolon) cages with stainless steel mesh bottoms and lids, such that there were five animals of a single sex per cage; 15 cages (five rows x three columns) were accommodated on each holding battery.

The room environment was controlled to give conditions within the temperature range 22±3°C and relative humidity 30-70%; a light/dark cycle of 12 hours operated throughout the study.

The animals were given free access to the experimental diets at all times and potable tap water (Anglian Water) was supplied to each animal cage by a polycarbonate bottle and a stainless steel sipper tube.

Route of administration:

oral: feed

Vehicle:

water

Details on oral exposure:

The diets were based on the ESL modified AIN-76A (MODAIN) diet. The test item was added to the diet in place of the starch component.

All diets were prepared at weekly intervals using the ESL diet room computer system and stored in the ESL chill room at 0-4°C. The diets remained in a UV lock (minimum 10 hours at ambient temperature) before delivery into the SPF unit where they were stored at approximately +4°C prior to use.

Analytical verification of doses or concentrations:

yes

Details on analytical verification of doses or concentrations:

The stability and homogeneity of the test item in the diet were investigated under Study number AH940234 (attached)

The test diets were sampled after preparation for week 1 (04 Jul 1994) and week 3 (18 Jul 1994) in order to confirm the achieved concentration of the test item in the diets.

The test item was extracted from the experimental diets with methanol. The extracts were then diluted with methanol such that the final concentration in the assay would be within the range of standards (4-20 ug/ml) prepared in methanol. Aliquots of the standards and samples were then pipetted into test tubes, concentrated to dryness under a stream of nitrogen and the residues redissolved in 2ml of deionised water. Analysis was carried out by the Methylene Blue Assay (MBAS) in which aqueous Methylene Blue reagent and chloroform were added to the sample and standard tubes and mixed thoroughly. After allowing the organic and aqueous phases to separate the optical density of the organic layer was measured at 650nm on a UV/Vis Spectrophotometer. Quantitation was achieved by comparison of absorbance values of the standards and samples, then applying the correction factor for a 93% recovery as determined in S~dy number AH940234.

Dose / conc.:

1 000 mg/kg diet

Remarks:

Equivalent to 0.1% in purified diet

Dose / conc.:

3 000 mg/kg diet

Remarks:

Equivalent to 0.3% purified diet

Dose / conc.:

10 000 mg/kg diet

Remarks:

Equivalent to 1.0% purified diet

No. of animals per sex per dose:

Three groups of ten male and ten female rats were fed 0.1 %, 0.3 % or 1.0% of test item 5 in purified diet for 28 days.

Control animals:

yes, plain diet

Details on study design:

Three groups of ten male and ten female rats were fed 0.1 %, 0.3 % or 1.0% of test item in purified diet for 28 days. A control group of ten male and ten female rats were fed the purified diet.

At the end of the study all rats were given a detailed necropsy and a range of tissues was taken for microscopic examination. Prior to necropsy, blood samples
were taken by cardiac puncture under Halothane anaesthesia for clinical pathology determinations.

Positive control:

Not applicable

Observations and examinations performed and frequency:

Measurements and observations during the live animal phase

Clinical signs
All animals were checked at least twice each day (once on Saturdays and Sundays) for signs of ill health or reaction to treatment. Such signs, including the time of onset, duration and intensity, were recorded on clinical signs sheets at the time of observation and then entered into the Xybion Pathtox system at the earliest possible time following the observation.

Body weight
Animals were weighed at weekly intervals (Tuesdays) throughout the study.

Food and water consumption
For each cage of five animals, food and water intakes were recorded twice-weekly (Tuesdays and Fridays) throughout the study and the weekly amounts calculated.

Sacrifice and pathology:

Blood collection and termination
At the end of the test period the animals were bled by cardiac puncture under Halothane anaesthesia. The blood was divided between three sample tubes: a plastic tube containing EDTA (potassium salt) for haematological analysis; a glass tube containing lithium heparin for plasma chemistry analysis; and a glass tube containing no anticoagulant for serum protein analysis and electrophoresis. The animals were then humanely killed by carbon dioxide inhalation.

Clinical Pathology

Haematology
The following haematological indices were determined using the Technicon HI *(A) haematology analyser:
Red blood cell count
Haemoglobin
Platelets
Total white blood cell count
Differential white cell count (lymphocytes, neutrophils, monocytes, eosinophils, basophils,
large unstained cells) ..
*Mean red cell volume (determined from the red cell volume histogram)
*Mean red cell haemoglobin (haemoglobin/red blood cell count)
*Haematocrit (red cell count x mean red cell volume)
*Mean red cell haemoglobin concentration (haemoglobin/haematocrit)

*Values were calculated

Reticulocytes were determined by manual counting after staining with New Methylene Blue.

Plasma chemistry

The following plasma clinical chemistry parameters were measured on the Hitachi 704EC:
Sodium
Potassium
Calcium
Magnesium
Chloride
Inorganic phosphate
Creatinine
Urea
Triglyceride
Glucose
Total cholesterol
Alanine aminotransferase (ALT)
Aspartate aminotransferase (AST)
Lactate dehydrogenase
Hydroxy butyrate dehydrogenase (HBD)
Alkaline Phosphatase (ALP)
Pseudocholinesterase
Creatine kinase
5' -Nucleotidase

Serum Chemistry

The following serum clinical chemistry parameters were measured on the Hitachi 704EC:
Total protein
Albumin
Albumin:globulin ratio (calculated)
The following parameters were determined by serum electrophoresis on cellulose acetate
plates followed by staining with Ponceau S and quantification of the fractions using the
Profil Ecran scanning densitometer:
Albumin
aI-globulin
a2-globulin
J3-globulin
y-globulin

Quality control
Internal quality controls were applied regularly to the measured clinical pathology parameters. These were performed after every tenth sample for the haematological indices and after every nineteenth sample for the clinical chemistry parameters. In the case of the serum protein electrophoresis, one sample was selected randomly each day and run repeatedly along with every seven specimens.

Necropsy

All animals were subjected to a detailed necropsy. All macroscopic abnormalities were recorded as well as an assessment of the level of intra-abdominal fat deposition. The following organs were removed and weighed: adrenal glands, brain, heart, kidneys, liver, spleen and testes. The ratio of organ weight to 100g of body weight was calculated in each case and recorded as relative organ weight. The following tissues were taken from each rat and preserved in 10% buffered formalin unless otherwise indicated:

Brain
Cervical lymph node
Mesenteric lymph node
Pancreas
Thymus
Ovaries
Fallopian tubes
Vagina #
Uterus
Cervix
Testes #
Epididymides #
Seminal vesicles #
Eyes $
Harderian glands $
Salivary glands #
Adrenal glands
Pituitary
Sciatic nerve
Thyroids
Parathyroids
Liver
Heart
Spleen
Lungs
Larynx
Trachea
Kidneys
Aorta
Bladder
Prostate
Tongue
Caecum
Stomach
Duodenum
Ileum
Jejunum
Colon
Rectum
Oesophagus
Mammary gland (site of)
Skeletal muscle
Skin
Femur and stifle joint
Spinal cord
Sternum
Head

# Tissues were preserved in Bouin' s fixative
$ Tissues were fixed in Davidson's fluid

Bone marrow smears were taken and stained with May-Grunwald Giemsa stain.

Histology

The tissues were processed into paraffin wax, using conventional histological methods, and sections nominally 4JLm in thickness were prepared and stained with haematoxylin and eosin (H&E) for microscopic examination.

Microscopic examination was performed on the above tissues from all control rats and all rats fed 1.0% of test item.

Histopathological findings were entered directly into the KMS V2 pathology software system.

During the examination of the tissues, histopathological changes were recorded as present or absent, or graded according to their morphology, using a numerical scale of 0 to 5, in order to assess degrees of severity or activity. This procedure provides a means of ranking degrees of change which may assist in the interpretation of biological differences. The actual scores obtained have no intrinsic value.

Statistics:

For continuous variables the significance of the differences amongst groups was assessed by analysis of variance. Differences between each treated group and the control group were assessed by Dunnett's test using a pooled error variance.

Clinical signs:

no effects observed

Description (incidence and severity):

Clinical signs observed during the study were ocular discharge, nasal discharge and penile haemorrhage. These signs did not show any treatment-related distribution and were considered to form part of the normal background findings seen in this type of study.

Mortality:

no mortality observed

Description (incidence):

There were no decedents during the course of the study.

Body weight and weight changes:

no effects observed

Description (incidence and severity):

The mean body weight gain of male rats fed 1.0% test item was decreased significantly during the last week of the study, when compared to controls. Although mean body weight of these animals at week 4, and the overall body weight gain, was
lower than the controls these differences were not considered to be statistically significant.

Food consumption and compound intake (if feeding study):

no effects observed

Description (incidence and severity):

The animals were housed in groups of five per cage and the food and water intakes were measured for each cage, therefore, there were insufficient data points for a statistical analysis to be carried out. However, examination of the data did not indicate any treatment-related effects on either food consumption.

Food efficiency:

not examined

Water consumption and compound intake (if drinking water study):

no effects observed

Description (incidence and severity):

The animals were housed in groups of five per cage and the food and water intakes were measured for each cage, therefore, there were insufficient data points for a statistical analysis to be carried out. However, examination of the data did not indicate any treatment-related effects on water consumption.

Ophthalmological findings:

not examined

Haematological findings:

no effects observed

Description (incidence and severity):

Red blood cell indices
No treatment-related changes were observed.

White blood cell indices
No treatment-related changes were observed.

Bone marrow smears
In the absence of any treatment-related changes in either the red or white blood cell counts, it was not considered necessary to examine the bone marrow smears.

Clinical biochemistry findings:

no effects observed

Description (incidence and severity):

Plasma electrolytes
No treatment-related changes were observed.

Plasma enzymes
Plasma alanine aminotransferase activity was increased slightly in both male and female rats fed 1.0% test item

Plasma metabolites
No treatment-related changes were observed.

Serum electrophoresis
No treatment-related changes were observed.

Urinalysis findings:

not examined

Behaviour (functional findings):

no effects observed

Immunological findings:

not examined

Organ weight findings including organ / body weight ratios:

no effects observed

Description (incidence and severity):

The group mean absolute spleen weight of male rats fed 1.0% test item was decreased in comparison with controls, but when related to terminal body weight no significant difference was observed. According to the study investigators, this could relate to the lower terminal body weight of these animals.

Gross pathological findings:

effects observed, treatment-related

Description (incidence and severity):

The only macroscopic finding showing a treatment-related distribution was a slightly increased incidence, in comparison to controls, of green caecal contents in female rats which received 1.0% test item. However, this was considered to be incidental and of no toxicological significance.

Male rats fed 1.0% test item showed a slight reduction in the group mean score for the quantity of abdominal fat, compared with controls.

Neuropathological findings:

not examined

Histopathological findings: non-neoplastic:

no effects observed

Description (incidence and severity):

No microscopic findings considered to be related to the administration of test item were observed.

The cortex of the kidneys of one male rat (D8) and one female rat (0110) which received 1.0% of Adinol CT95 showed peritubular proliferation of stem cells.

A variety of other spontaneous changes was recorded in both control and treated animals. These findings were within the spectrum of spontaneous lesions commonly encountered in laboratory rats of this age and strain, showed no evidence of a treatment-related distribution in incidence or severity and were considered to be unrelated to the feeding of test item.

Histopathological findings: neoplastic:

no effects observed

Other effects:

no effects observed

Key result

Dose descriptor:

NOAEL

Effect level:

>= 500 mg/kg bw/day (nominal)

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: The daily oral (dietary) administration of test item to rats (Sprague Dawley) did not produce any toxicological changes considered to be related to treatment. The no-effect level was greater than 1.0% diet equivalent to 500 mg/kg bw/d

Dose descriptor:

NOAEL

Effect level:

>= 10 000 mg/kg diet

Based on:

test mat.

Sex:

male/female

Basis for effect level:

other: The daily oral (dietary) administration of test item to rats (Sprague Dawley strain, bred at Harlan UK Ltd.) did not produce any toxicological changes considered to be related to treatment. The NOEL was greater than 1.0% of test item in the diet.

Key result

Critical effects observed:

no

CHEMICAL ANALYSIS

Characterisation and stability of the test substance

This was carried out under study number AC940233; the test material was found to be table over the study period.

Stability and homogeneity of the experimental diets

The test material was found to be homogeneously dispersed in the diet at concentrations of

0.1, 0.3 and 1.0% (w/w) of test item under Study number AH940234. The same concentrations were found to be stable in the diet formulation for 14 days.

Achieved concentration

On both occasions the measured concentrations for the diets prepared at all three levels, were found to be within ±10% of the nominal concentration, when the correction factor for a 93% recovery, as determined in Study number AH940234, was applied.

Environmental conditions

Animal room environmental measurements showed that for the duration of the study, temperature and humidity were maintained within the limits specified.

Pre-test health check

Twelve animals (nine male and three female) were found to have total white cell counts in excess of 12.0 x10⁹/L, the preferred maximum value; these animals were rejected on health

grounds prior to the start of the study.

Conclusions:

The daily oral (dietary) administration of the read-across source substance sodium methyl cocoyl taurate (SMCT) to rats (Sprague Dawley strain, bred at Harlan UK Ltd.) did not produce any toxicological changes considered to be related to treatment. The no-effect level was greater than 1.0% of SMCT in the diet, equivalent to 500 mg/kg bw/d.

This study for the source substance SMCT is used as read-across to the registered (target) substance SMLT. See section 13 for the full read-across justification.

Executive summary:

A repeat dose study was carried to determine the toxicity of the source substance sodium methyl cocoyl taurate (SMCT) to rats exposed via the diet according to OECD TG 407. Groups of ten male and ten female rats were fed either 0.1 %, 0.3% or 1.0% (w/w) of SMCT in purified dietad libitum for 28 days. A control group of ten male and ten female rats were fed the purified diet. The animals were observed up to two times per day for signs of ill health or reaction to treatment. Body weights were recorded at weekly intervals throughout the study; food and water intakes were measured twice-weekly and the weekly consumptions calculated. At the end of the treatment period all the rats were humanely killed and subjected to a detailed necropsy, at which stage a number of organs was weighed and a range of tissues was taken for histological examination. Prior to necropsy, blood was removed for clinical pathology determinations.

The body weight gain of male rats fed 1.0% of SMCT was decreased significantly during the last week of the study but the final body weight and overall body weight gain was not significantly affected. Plasma alanine aminotransferase was increased in both male and female rats fed 1.0% of SMCT but no treatment associated pathological changes were observed in the liver. The group mean absolute spleen weight of male rats fed 1.0 %w/w of SMCT was decreased in comparison with controls, but when related to terminal body weight no significant difference was observed. The only macroscopic fmding showing a treatment-related distribution was a slightly increased incidence of green caecal contents in female rats fed 1.0% of SMCT, in comparison with controls. Male rats fed 1.0% of SMCT had a slight reduction in the group mean score for the quantity of abdominal fat present compared with controls. Histopathological examination did not reveal any microscopic findings which were considered to be related to the administration of SMCT.

In conclusion, the daily oral (dietary) administration of SMCT to rats did not produce any toxicological changes considered to be related to treatment. The NOAEL from this study was established as being greater than 1.0% of SMCT in the diet, equivalent to 500 mg/kg bw/d.

This study for the source substance SMCT is used as read-across to the registered (target) substance SMLT. See section 13 for the full read-across justification.

 

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

NOAEL

500 mg/kg bw/day

Study duration:

subchronic

Species:

rat

Repeated dose toxicity: inhalation - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: inhalation - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - systemic effects

Endpoint conclusion

Endpoint conclusion:

no study available

Repeated dose toxicity: dermal - local effects

Endpoint conclusion

Endpoint conclusion:

no study available

Justification for classification or non-classification

The daily oral (dietary) administration of the read-across source substance sodium methyl cocoyl taurate (SMCT) to rats (Sprague Dawley strain, bred at Harlan UK Ltd.) did not produce any toxicological changes considered to be related to treatment. The no-effect level was greater than 1.0% of SMCT in the diet, equivalent to 500 mg/kg bw/d.

This study for the source substance SMCT is used as read-across to the registered (target) substance SMLT. See section 13 for the full read-across justification.